Certain operative procedures, particularly laparoscopy, hysteroscopy, endoscopy and coeloscopy, require the insertion into a body cavity, such as the abdominal cavity, of the objective lens of a laparoscope, endoscope, coeloscope or similar telescope in order to view features and structures within the body cavity and/or to view diagnostic or operative procedures carried out within the cavity.
Such telescopes usually consist in part of a rigid or relatively rigid rod or shaft of approximately 300-500 mm length, with an outer diameter of 5 mm to 11 mm, having an objective lens at one end and an eyepiece at the other end. The rod or shaft of the telescope contains light-transmitting glass fibres and/or rod lenses.
A prerequisite for the utilisation of such telescopes is the illumination of the structures within the body cavity with clear, bright light. To achieve this, the telescope also normally has a connection, adjacent to the eyepiece, for the attachment of an external light source which provides illumination, via light-transmitting fibres within the telescope, of the features within the body cavity.
Prior to the introduction of the telescope, the body cavity is generally inflated with a gas, usually carbon dioxide, using a gas insufflator. Subsequently a plastic or metal sleeve or sheath, often referred to as a trocar, is inserted through the wall of the cavity. These sleeves contain a means of making a seal to prevent the leakage of gas from within the body cavity. The end of the telescope containing the objective lens is inserted into the body cavity through the sleeve, the attached light-source activated and the features within the body cavity viewed through the eyepiece of the telescope or on a video monitor receiving signals from a video camera attached to the eyepiece.
The objective lens of the telescope often becomes soiled during operative procedure. Tissue particles, blood and other body fluids attach to the lens and obscure vision. In these instances, the telescope has to be removed from the body cavity and the objective lens wiped clean with a suitable cloth. During some operative procedures, the telescope may have to be removed frequently to have the lens wiped clean.
The loss of vision due to soiling of the objective lens of the telescope is a serious complication if the source of soiling is blood from a transected blood vessel, particularly an arterial vessel. The covering of the objective lens of the telescope by arterial blood is often referred to as the "red video" sign. This is particularly serious if the bleeding is extensive. The lens might be repeatedly obscured by blood or the bleed be so extensive as to not allow enough time to safely remove the telescope to wipe the lens. In such cases the procedure is often converted to an emergency "open" operative procedure.